1. Field of the Invention
The present invention relates to a weight member for a golf club head.
2. Description of Related Art
A typical golf club head body for a golf club head usually adopts a material having a high coefficient of restitution to allow a golf ball stricken by the golf club to fly through a longer distance. Since a material with a high vibration-absorbing capacity may absorb most part of vibration of the golf club generated as a result of striking a golf ball, titanium or titanium alloy is often selected as the material for reducing the vibration transmitted to the hands of the golfer even if the golf ball is not hit by the sweet spot of the striking plate of the golf club head. Nevertheless, since titanium has a density of about 4.51 g/cm3, the center of gravity of the golf club, which is a product of assembling a shaft with a golf club head that uses titanium (such as 6-4 Ti) as the main composition, is not in an appropriate location. A solution to this problem is inserting a weight member into the golf club head to adjust the location of the center of gravity.
FIG. 1 of the drawings illustrates a golf club head body 1 having a recession 11 and a weight member 2 to be embedded by tight fitting into the recession 11. Then, surface finishing is performed on the golf club head body 1 and the weight member 2 to provide a golf club head. The weight member 2 is made of a material that has a high density and that is rigid and fragile. The precision formation of the weight member 2 for mating with the recession 11 of the golf club head body 1 is difficult, and the weight member 2 is apt to break while pressing the weight member 2 into the golf club head body 1. Further, a gap between the recession 11 and the weight member 2 is generated after the surface finishing and thus requires subsequent filling of the gap. The tight engagement between the surfaces of the golf club head body 1 and the weight member 2 are adversely affected. Further, since the filling material for filling the gap between the recession 11 and the weight member 2 is a high molecular polymer, the weight member 2 tends to disengage from the golf club head body 1 after long-term striking of golf balls for a period of time.
FIG. 2 shows another conventional golf club head, wherein a weight member 4 is placed in a recession 31 of a golf club head body 3 and then fixed in place by welding. Although the engaging strength between the golf club head body 3 and the weight member 4 is improved by welding, the high temperature generated during welding causes melting of both the golf club head body 3 and the weight member 4, variation in the welding pool disturbance, welding speed, electric current, and heat transmitted to the golf club head body 3 and the weight member 4 affects the depth of the welding bead 32. As a result, the welding bead 32 is irregular in shape, resulting in difficult quality control and adversely affecting the appearance. Further, in a case that the golf club head body 3 is made of titanium or titanium alloy, the welding heat checking often occurs, as titanium has a poor welding effect with other metal. In particular, titanium can only be welded with zirconium, niobium, tantalum, and hafnium.